1. Field of the Invention
The present invention relates to a device for controlling a motor in a washing machine and a method for controlling a process of a washing machine by using the same.
2. Background of the Related Art
In general, the washing machine is a home appliance for washing laundry by friction caused by circulation of washing water occurred as the washing water is forced circulated, and softening action of detergent, and has in general, washing, rinsing, and spinning cycles.
The washing machine illustrated in FIG. 1 is provided with a washing shaft divided into an upper washing shaft 3b and a lower washing shaft 3c. The upper washing shaft 3b has a pulsator 3a connected to a top end thereof, and the lower washing shaft 3c has a pulley boss 3d connected to a lower end thereof, to which an induction motor (not shown) is coupled through a belt and a pulley (not shown). The washing shaft 3b and 3c is in a spin shaft 4a and a gear housing 4b, both are hollow.
The washing machine is operative as follows.
The pulsator 3a is designed selectively rotatable depending on the washing cycle and the spinning cycle by operating a clutch 6 by turning on/off a separate motor (not shown). As shown in FIG. 2A, in the washing or rinsing cycle, the gear housing 4b and the pulley boss 3d, i.e., the washing shaft 3b and 3c and the spin shaft 4a, are separated as a separate motor connected to the clutch 6 is turned on, to insert the clutch 6 in a groove and fasten the clutch 6 thereto. Then, as the spin shaft 4a is fixed, and the rotation of the induction motor (not shown) is transmitted to the upper washing shaft 3b in continuation to the lower washing shaft 3c, only the pulsator 3a is rotated in regular/reverse directions, to carry out the washing.
On the other hand, as shown in FIG. 2B, in the spinning cycle, when the motor connected to the clutch 6 is turned off, to separate the clutch 6 from the bearing housing 5a, and couple the gear housing 4b and the pulley boss 3d with the clutch 6, the rotation of the induction motor is transmitted both to the washing shaft 3b and 3c and the spin shaft 4a, to rotate an inner tub 2 and the pulsator 3a at a high speed, thereby extracting water from the laundry.
A driving circuit of the washing machine operative as above will be described.
Though a drawing illustrating a related art washing machine driving circuit is omitted, the related art washing machine driving circuit using an induction motor is provided with a control part for detecting a process mode a user provided thereto, and providing control signals according to the process mode, a driving part for providing a switching signal to drive the induction motor in response to the control signal from the control part, a switching part for switching in response to the switching signal from the driving part, and a condenser for generating a rotation torque of the induction motor according to the switching action of the switching part.
The operation of the driving circuit will be described. When the user provides power to the washing machine, selects a process mode suitable for kind and an amount of laundry introduced into the washing tub, and carries out the washing, the control part (microcomputer) detects them, and provides control signals according to a pertinent algorithm preset therein.
In response to the control signals from the control part, the driving part drives the clutch and the induction motor by means of switching action, to drive the inner tub 2 and the pulsator 3a selectively to carry out a selected process mode. In this instance, the rotation torque of the induction motor is dependent on a capacity of the condenser, and the capacity of the condenser is fixed in designing the driving circuit of the washing machine.
Since the condenser capacity is not variable once fixed in the related art washing machine, unable to vary the torque at a given rotational speed, it has been impossible to implement a variety of algorithm.
Moreover, since the torque of the induction motor is not variable, it has been impossible to cope with load variation following rotation of the pulsator in a washing cycle, and rotation both of the inner tub and the pulsator in the spinning cycle.